1. Field of the Invention
The present invention relates to the field of electrostatic discharge (ESD) and power clamp circuits; more specifically, it relates to ESD and power clamp circuits tunable to unity current gain cutoff frequency (fT) and collector to emitter with base open breakdown voltage (BVceo).
2. Background of the Invention
The manufacture of high performance bipolar transistors requires reduction of the vertical profile as well as reduction of transistor parasitics. In order to reduce the collector transit time of the carriers, the subcollector is placed close to the collector-base junction. As the base and collector regions are moved closer together, the collector-to-emitter breakdown voltage, BVceo, decreases and the frequency response of the transistor, fT, increases. In ESD applications, there is a need to be able to provide both a low capacitance device, or a device with a different breakdown voltage than the standard device which requires protection.